Slug-loaded shotgun cartridge



Oct. 16, 1962 W. TANNER ET AL 3,058,420

SLUG-LOADED SHOTGUN CARTRIDGE Filed Sept, 22, 1960 UnitedStates Patent O M The present invention relates to slug-loaded shotgun cartridges and particularly to such cartridges in which the slug has a base with a relatively large concentric cavity.

A slug having a base with a relatively large concentric l cavity has advantages over a solid projectile of substantially similar caliber and Weight. Such a slug has a forward location of the centre of gravity, of importance in stablising it during flight and also, lbecause of the cavity in its base the slug may be constructed with a longer, cylindrical tenon portion to assist in guiding it through the bore of a shotgun.

A limiting factor in the performance of such shotgun slug shells is the accuracy with which the slugs may be fired. Accuracy is affected by deformation which t-he slug Isuffers upon acceleration in the bore of a shotgun. Under the effect of the high stresses in the bore the metal of the slug tends to ow kand this is likely to cause a permanent shortening of the slug, andconsequent thickening of its Walls accompanied by a reduction of the base cavity.v Since any deformation will be uncontrolled, the symmetry of the slug about its longitudinal axis is likely to be affected tending to cause erratic flight.

One measure of the performance of a slug-loaded shotgun cartridge is the group? size. YThis group size relates to the extreme spread between any two of a group of slugs fired to strike a target at a given distance. Cert-ain standards of distance and spread have been established and serve as criteria by which the cartridges (and so the accuracy of the slugs) are judged.

It is an object of the present invention to provide an improved slug-loaded shotgun cartridge.

Another object of the present invention is to provide a slug-loaded shotgun cartridge of improved accuracy.

A further object of the invention is to improve generally the ballistic performance of slugs (caused by uncontrolled deformation of the slug in the bore of a shotgun).

Still further objects will appear from the detailed description taken in connection with the accompanying drawings, in which:

FIG. l is a longitudinal sectional view of a slug-loaded cartridge embodying the present invention;

FIG. 2 is a similar View illustrating the preferred embodiment of the present invention; `and FIGS. 3, 4, 5 and 6 illustrate, in section, various designs of a slug and its accompanying support (as defined hereinafter) which may Ibe used in practising the present invention.

According to the present invention an improved shotgun slug shell is provided having a tube, within the tube a propellent charge and a slug having a base cavity, a wad between the propellent charge and the slug and means to retain the slug within the tube, in which the improvement comprises a solid support of density below that of the slug substantially contiguous with the base of the slug and the surface of the cavity therein.

The support is preferably provided by a resilient material of relatively low density, such as a mixture of sawdust and latex which may be packed into the base cavity of the slug. A particularly satisfactory support may be obtained by moulding plastic substances such as polyethylene or polypropylene to the desired shape. However, the support may be made of any materialy such as 3,058,420 Patented Oct. 16, 1962 lCe wood, mouldable polymeric resins including rubbers or even sponged light metals, which is solid and resists distortion.

A complete understanding of the invention may be obtained from the following detailed description of a structure constituting a specific embodiment of the invention, read in conjunction with the accompanying drawings.

Referring now to FIG. l of the drawings, a tube 1 formed of convolutions of paper or other suitable material is assembled with a metallic base cup 2, la priming assembly 3 and a base wad 4. A propellent charge 5 is located within tube I above base wad 4 and one or more resilient filler wards 6 (6A-6C in FIGURE l) are placed over and in contact with the top of the propellent charge 5. r[The resilient filler wad(s) 6 are in the form of cylinders cut from consolidated fibrous sheet material, such as heavily calendered paper board or felting. Impregnating of the sheet material with, for example, a parain of high melting point is desirable.

Above the filler wads 6, a metal slug 7 and support 8 is insertedV and the mouth of the shell is closed by a closure 9 integral with the side of the tube 1, by infolding the tube 1 near its mouth. The closure 9 may be rendered water resistant by the application of a suitable sealing composition.

The objects of the present invention are obtained primarily by providing support to substantially all of the base surface area of the slug, including the surface area of the base cavity. As mentioned abovethis support may be provided, as illustrated in FIG. 3, by a mixture of sawdust and latex (8A) or, as illustrated in FIGS. 1, 2 and 4, by an insert (8B, 8C or 8D) moulded to suitable dimensions from polyethylene. In FIG. 3, the base portion 11 must be in direct contact with the uppermost of filler wads 6 whilst the remaining base surface area of the slug, namely that provided by the cavity, is supported =by mixture 8A which in turn must bear directly upon the top of the column of filler wads 6.

When the support 8 is moulded from, for exmple, polyethylene, it may be moulded to a variety of shapes as illustrated in FIGS. l, 4, 5 or 6 provided always that support -for substantially all of the base surface area is obtained.

In order to facilitate sequential assembly of the shotgun cartridge, the support is preferably equipped with a thin ange 12 (FIGS. l, 2 and 4) of a diameter approaching that of the tube 1.

The preferred slugs of the present invention are the conventionally rifled slugs, usually made of lead or lead alloy, and these are identified by the flutes or ribs on the tenon portion of the slug. These liutes or ribs can, however, be dispensed with and, moreover, the present invention may be practiced with slugs of substantially different design as illustrated in FIGS. 5 and 6 of the drawings.

lln the cases illustrated in FIGS. 5 and 6, the slug 7 is sufficiently small in outer diameter to be surrounded by a thin walled tubular mantle 13 integral with the support 8C and 8D respectively. The outer diameter of the mantle 13 must then be such as to provide the proper fit with tube 41 of the shotgun cartridge. With the designs of slug and support illustrated in the latter figures, barrel fouling is greatly reduced or even eliminated since the slug is not in contact with the barrel of the gun at any time.

The support illustrated -in FIG. 6 is moulded from polyethylene in such a Way that it is capable of interlocking with a slug 7 having a truncated conical cavity. A radial groove 14 is provided in the support 8D. On firing of a shotgun cartridge containing such a slug and support, the slug will tend to deform and material near its base will flow into the radial groove 14.

The accuracy of any of the slug-loaded shotgun cartridges described above may be still further improved by interposing a flanged disc between the upper stratum of the propellent charge and the bottom of the column of filler wads.

This preferred embodiment is illustrated in FIG. 2 of the drawings. The flanged disc y10 may be formed of consolidated fibrous `sheet material or it may be moulded from a suitable plastic material such -as polyethylene. The depth of the ilange need not be larger than 0.15 since a substantial increase in depth may increase assemybly difliculties. It is, however, important that the flange be suiciently deep to allow for an optimum seal between the disc 10 and the tube 1.

The advantageous results obtained with shotgun cartridges constructed in accordance with the present invention are illustrated in the following table of comparative test data from which it will be noted that an appreciable improvement of the accuracy is obtained.

Sample A was of cartridges of conventional construction (ordinary column of wads and unsupported slug).

Sample B was of cartridges of conventional construction in which, however, a flanged disc had been interposed between the propellent charge and the column of wads.

Sample C was of cartridges according to the present invention (supported slug).

Sample D was of cartridges according to the preferred embodiment of the present invention (supported slug in conjunction with flanged disc interposed between the propellent charge and the column of wads).

All cartridges Were of 12 gauge, although the invention is applicable to any of the conventional gauge sizes of shotgun cartridges.

What we claim is:

A slug-loaded shotgun cartridge comprising, in combination, a casing closed at one end to form a breech closure, within said casing a propellent charge and a titled slug having a base cavity, a flanged disc seated upon the upper stratum of said propellent charge, a series of wads between said flanged disc and said slug, a solid support of density below that of said slug substantially contiguous with the base of said slug and the surface of the cavity therein, said support being composed of moulded synthetic polymer selected from the group consisting of polyethylene and polypropylene, and a closure integral with said casing at its other end to retain said slug within said casing.

References Cited in the le of this patent UNITED STATES PATENTS 290,230 Haviland Dec. 18, 1883 1,063,905 Beckmann June 3, 1913 1,518,920 Halloran Dec. 9, 1924 2,414,863 Foster Jan. 28, 1947 2,820,412 Beeuwkes et al Jan. 21, 1958 2,894,456 Olin .Tuly 14, 1959 2,920,563 De Caro Jan. 12, 1960 FOREIGN PATENTS 828,459 France Feb. 14, 1938 830,963 France May 23, 1938 

